Appendix S1 We calculated species accumulation curves for each sampling unit (transect; n = 64), using the inventories obtained in their corresponding 30 pitfall traps.

Figure S1 Location of the nine islands in the Azorean archipelago, aligned in a WNW ESE direction. The study islands are highlighted (Flores, Faial, Terceira and Santa Maria), where a detail of the surface area occupied by native forests is also indicated in grey.

Table S1 Bray–Curtis index of similarity values of the whole epigean arthropod assemblages and only considering the indigenous species performed on 15 rarefied matrices (from 1 to 15; see Methods), for all habitats, and separately within each habitat: native forests (Natf), exotic forest (Exf), seminatural pastures (Seminpast) and intensive pastures (Intpast). Significant differences between the whole assemblage and the indigenous species similarities are also indicated after Wilcoxon matched pair tests.

Table S2 Pseudo-F values of two-way crossed permanova analyses performed on 15 rarefied matrices (from 1 to 15; see methods), indicating the pseudo-F values for the differences in assemblage similarity in the composition of sampling units according to the two considered factors (habitats and islands) as well as their interaction.

Table S3 Pseudo-F values of two-way crossed permanova analyses performed separately on the ten most abundant species of the indigenous and exotic species using the non-rarefied original data, indicating the pseudo-F values for the differences in assemblage similarity in the composition of sampling units according to the two considered factors (habitats and islands) as well as their interaction (habitat x island).

Table S4 Coefficients of variation of the 20 most abundant indigenous and exotic species captured per island and per considered habitat.

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